About This Item
Share This Item
Continent and Ocean Basin Evolution by Sea Floor Spreading: Abstract
Sea floor spreading is envisioned as the fundamental process creating continents and ocean basins. Accordingly, the sea floor moves out in opposite directions from the mid-ocean rises. The gap is filled by new strips of sea floor created from the ultra-basic mantle. By this giant conveyor-belt action proto-continental rock is eventually piled up as rafts of sial; continental is lands in the world encircling sima. Thermal convection cells in the mantle provide the fundamental driving force and the mid-ocean rises mark their divergence while the continents tend to lie over the convergences. The principle novelty of this concept is that no fixed layer separates the sea floor from the convection process; rather the ocean bottom is the exposed and outcropping limbs of this convection. Accordingly, it is useful to consider the supra-mantle substance beneath the ocean (serpentine and spilite plus sediment) as only a "rind" . In contrast the bouyant sialic continents ride above this convection and are not invaded by it so that they alone are the true crust.
Although perhaps alarming at first thought, sea floor spreading is an orderly, evolutionary and actualistic process consonant with geologic history. Continents grow in area and thickness with time, and the volume of the ocean basins increase as well to accommodate juvenile water. The continents are domains of compression and the ocean basins domains of tension; but the earth as a whole neither contracts or expands. Contiental drift occurs with the continents tending to move to convergence zones. The apparent youth of the sea floor is explained by the destruction of the old floor and replacement by new sea floor. A new rationale is offered for the development of geo-synclines, to explain continental slopes, etc.
Acknowledgments and Associated Footnotes
1 U. S. Navy Electronics Laboratory, San Diego, California
Copyright © 2006 by the Tulsa Geological Society